Patent GB-1341360-A (GB)
Title: Phased-array antenna
IPC: G01S13/42
Filed: 1972-04-07
Abstract: 1341360 Digital ferrite phase-shifters SYRACUSE UNIVERSITY RESEARCH CORP 7 April 1972 16115/72 Heading H1W [Also in Division H4] In a phased-array aerial system radiating elements are associated with respective phaseshifters which each comprises a plurality of individual ferrite units of different sizes, to introduce phase shifts in a series of binary bits. The ferrite unit which introduces a phase shift corresponding to the minimum bit is of a size to introduce a phase shift equal to 360 degrees divided by 2<SP>n</SP>-1, where n is the number of ferrite units in each phase-shifter. As described, a radar aerial array consists of seventeen columns of eight vertically arranged dipoles, each column being fed through a four-bit non- reciprocal ferrite phase-shifter from a T-R switch. Beam steering is effected by providing complementary graduated phase shifts to each pair of columns which are equally disposed about the centre column, the phase shift of the latter being kept constant at 0 degrees. A phase shift increment of 24 degrees is used, since this allows one set of control apparatus to be used per column pair, as any digital setting and its complement then represent complementary phase settings, e.g., 0010 and 1101 represent 48 degrees and 312 degrees (or +48 degrees). Each phaseshifter comprises a meander line ML, Fig. 6, which is encapsulated in low-loss polyolefin dielectric material, and four ferrite toroids LW which are positioned over the encapsulated line, and which provide respective-delays of 192, 24, 48, 96 degrees. There are insulating spacers I between adjacent toroids, and individual switch wires LW and a common reset wire are provided. The phase-shifter is contained between metal ground planes, wity interposed insulation (Fig. 5, not shown). Driver circuits for the phaseshifters feature storage capacitors which are charged when a radar pulse is transmitted, and provide energy during switching and resetting times (Fig. 8, not shown). The phase-shifters of each symmetrically disposed pair of dipole columns N,N<SP>1</SP>, Fig. 7, are associated with a 4-bit flip-flop type digital counter, with both normal one (1) and inverted zero (0) outputs, which is driven from a distributer (Fig. 1, not shown) with a number of pulses proportional to the distance of either column from the centre. The counter outputs are coupled to gating circuits, and are selected as appropriate, according to whether it is a transmit or a receive phase-shifter setting. The outputs of the gating circuits trigger the driver circuits for setting the phaseshifter toroids or elements to the right states. The switch wires from the said driver circuits, and the reset wire from a dual reset driver circuit, are taken in opposite directions through the two phase-shifters, in order to obtain the requisite complementary functioning thereof. An operating sequence is as follows: (a) all elements of the L.H. phase-shifters are reset to (1) state and those of the R.H. phase-shifters are reset to (0); (b) transmit phase-shifter settings are entered: element state changes are from (1) to (0) on L.H. phase-shifters, and from (0) to (1) on R.H. phase-shifters; (c) the radar transmits a pulse; (d) resetting as in (a) above is effected; (e) receive phase-shifter settings are entered (these are complementary to the transmit settings) and remain until the next radar pulse period.